A NEW, LARGE, LATE PLEISTOCENE DEMOSPONGE FROM SOUTHEASTERN FLORIDA

Abstract

Spectacular exposures of large, upright, vase- to barrel-shaped, late Pleistocene sponges are dramatically exposed as part of the Miami Limestone along margins of the C-100C Canal in east-central Miami-Dade County, southeastern Florida. The discovery of this sponge reef by K. J. Cunningham was made in 2004, during a routine drive across the bridge above the C-100C Canal on S.W. 97th Avenue in Miami-Dade County, southeastern Florida. A second location, where comparable sponges are exposed in walls of a burrow lake, was also discovered by K. J. Cunningham in 2004 upon visiting the site after personal communication with L. Noblick, Montgomery Botanical Center, and S. Zona, Fairchild Tropical Botanic Garden, about similarly shaped geologic structures. Subsequently, the C-100C Canal location was documented and some of the sponges were collected and thin sections and samples were sent to J. K. Rigby for examination and evaluation. This paper, on the description and possible taxonomy of the sponges, is a result of that joint effort. Sponges reported here were collected from banks of Canal C-100C, of the Cutler Drain System, near the bridge of S.W. 97th Avenue, which crosses over the canal. That site is at 25°38′58.9″ North Latitude, and 80°21′02.3″ West Longitude, referenced to the North American Datum of 1983. At this location the sponge reef is exposed on the north bank of the canal. Completion of construction of the bridge on S.W. 97th Avenue over the canal was in 1966 so, presumably, the sponge reef has been exposed there for almost 40 years, at least. Unfortunately, detailed coordinate positions of all the sponge samples were not taken as they were collected. However, they would have come from only a few meters east of the SW 97th Avenue bridge, on either the northern or southern bank of the canal, or up to 250 …